Co-Promoted In₂O₃/ZrO₂ Integrated with Ultrathin Nanosheet HZSM-5 as Efficient Catalysts for CO₂ Hydrogenation to Gasoline

Carbon dioxide (CO 2 ) hydrogenation to gasoline through the methanol-mediate route using the metal oxide/ZSM-5 tandem catalyst has attracted considerable attention to reduce the pernicious effect of CO 2 on global climate change and to reduce our dependence on fossil fuels. The C 5 + molecules are preferred to pass through the straight channels of ZSM-5 zeolite, where side reactions may occur on the acid sites and the catalyst is deactivated due to pore blockage. Thus, the thickness of ZSM-5 along the straight channel, namely the b -axis direction, is crucial to manipulating the product distribution and catalyst lifetime. Here, HZSM-5 nanosheets with different thicknesses (2 nm to 2 μm) along the b -axis were synthesized controllably and composited with In 2 O 3 /ZrO 2 as tandem catalysts for CO 2 hydrogenation to gasoline. In 2 O 3 –ZrO 2 /HZSM-5 with a thickness of 20 nm shows the highest selectivity toward C 5 + hydrocarbons under isoconversional conditions and no deactivation after 150 h of reaction with less carbon deposition compared with the 2 μm one. Comparative activity tests and characterization results demonstrate that an appropriate length of straight channels can benefit the production of C 5 + hydrocarbons through the polymerization of short-chain molecules while preventing the cracking of long-chain hydrocarbons on acid sites. Adding an appropriate loading of Co into tandem catalysts with optimal composition gives rise to further enhancement in CO 2 conversion by 10%, and a slight increase in C 5 + selectivity. This can be attributed to the Co-induced hydrogen spillover from metallic Co to support ZrO 2, facilitating the formation of the key intermediate and its subsequent hydrogenation steps. This study provides insights into designing effective and anti-carbon deposition tandem catalysts for CO 2 -to-gasoline by manipulating the channel length–resident time–acidity relationship and the promoter effect.